1. Field of the Invention
The present invention relates to an image forming apparatus that includes a facsimile, a printer, a copying machine, or a multifunction peripheral (MFP).
2. Description of the Related Art
Conventionally, in an image forming apparatus that includes a facsimile, a printer, a copying machine, or an MFP, Japanese Patent Application Laid-open No. 9-274156 discloses the technology in which the phases of rotation reference clocks of a plurality of polygon motors are changed so as not to make a registration shift corresponding to a period of time of performing one scanning in a sub-scanning direction, and a synchronization detecting signal is generated so as not to overlap the timing for turning ON a sub-scanning synchronization signal (a print start signal), thereby preventing the occurrence of an image deviation by almost one scanning pitch in the sub-scanning direction.
However, there has been a problem in that hardware for changing a phase of a reference clock so that timing for turning ON a sub-scanning synchronization signal does not enter a range of time difference of the synchronization detecting signal (a variation range is included) becomes complex in the image forming apparatus according to the related art described above.
In view of the above problem, there is a need that a print start signal can be issued while a synchronization detecting signal for detecting a plurality of colors is not issued.